Apparently this is an actual product, made in Italy by an outfit called KiSkin:

The sun tattoo could be a tan or a burn, depending on how long it took to get, but it’s very cute either way. I wonder if they make one with a lattice pattern, short slits along the very outside curve of her cheeks, so she can get sun-tanned faux caning marks?

When I was in high school there was a brand of swimwear called HangTen that featured little cut-out footprints on the front hip part of the bikini bottom. I used to love my little HangTen footprints, but they would have been even cuter on my bottom.